the bug occurs only in Mac OS 10.6 (Snow Leopard) with a Guest Account that was created in Mac OS X 10.5 (Leopard). After upgrading to Snow Leopard, the Guest Account settings retain Leopard’s older spots, to coin a phrase. And there the problem lies.

Ouch! That's totally not good! I do manual backups of my Mac to two separate NAS's, I was planning to upgrade to Snow Leopard after Windows 7 comes out (and install Windows 7 on my Mac after upgrading to Snow Leopard), think I'll get an additional desktop HD and do a Time Machine backup prior to the upgrade!